1. Field of the Invention
This invention relates to the art of tank vehicles, particularly railroad tank cars and specifically deals with tank cars formed from a spirally wound steel plate strip with adjoining edges of the strip united by a continuous spiral weld.
2. Prior Art:
Conventional tank car constructions include the bending of steel plates into cylinder form, the joining of the adjacent ends of the plates with a longitudinal weld, and the welding together of the resulting tubes or hoops in end-to-end abutted relation with circumferential weld bonds. These constructions have flat or out-of-round areas along the longitudinal welds, mis-matches in adjoining tubular sections producing sumps and humps and always result in a plurality of weak T-shaped weld sections where the longitudinal weld seams join the circumferential weld seams. This conventional end-to-end cylinder tank construction is expensive, its assembly requires considerable shop floor space because of the number of work stations that are required, results in out-of-round dimensional variations, involves considerable scrap loss and requires weakened weld sections.
It would therefore be an improvement in this art to construct portable tanks for tank cars, and the like by spirally coiling a steel plate strip or ribbon into tube form with a continuous weld seam uniting abutting edges of the strip.